Shift sensor questions

pharpe

New Member
Region
USA
I have a BPM F-95 with a Bafang Ultra mid drive motor. I've been having quite a bit of trouble with hard chain skip when shifting. I know I need to stop pedaling to take the force of the chain while shifting. But, when going fast (~20+ mph) or under hard acceleration like when pulling out in traffic or climbing, I'm still having issues. It's like there is a slight delay between when I let off the pedals and when the motor stops. Even though I'm not putting force down on the pedals the motor still is. The bike does not have a shift sensor currently and I'm wondering if adding one would help with this? Or do I just need to start taking a longer pause between shifts? Hoping it not the latter because that really limits my ability to accelerate and climb effectively if a 2 second pause is required between shifts.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Pretty sure this is something you'll get used to. It's a timing thing. It may seem like a couple of seconds at first, but I'm betting you can have it down to something that will be much more natural soon.

Been riding bikes that require shifting for a long time, so even though my bike has the shift detector, I do the pause thing anyway. I am NOT stopping my pedal motion, but I am pausing the pressure placed on the pedals until I feel the shift if that makes any sense?

Something else that helped while climbing for me (especially at low speeds where it's so easy to stall the bike), is rather than attempt a shift, I punch the "up" button. This for a MUCH smoother increase in power, with no possibility of a blown shift. Thought here is you HAVE the power on tap..... -Al
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
If you have a UART Ultra there are a few programing changes that can be made to make shifts smoother.
Also as things are now with the motor delay in slowing down as you stop pedaling, you can time it a little better for smoother shifts
As Al said.. it is all in the timing so try adding a split second more from the time you stop pedaling to the time you shift. You should be able shift smoothly with the motor as it's just about to stop.
 

voidedwarranty

Well-Known Member
My bbshd has a shift sensor and I feel it works great. Worked so well I could actually hold full throttle and knock off up shifts without any adverse chain issues. Still works well after converting to IGH. In fact the entire action of shifting with the IGH and shift sensor works so well I don't even have to stop pedalling. Feels like the bike equivalent of a dual clutch transmission in a sports car.